This is a descriptive analytical study to investigate the prevalence and risk factors for pancreatitis after Endoscopic Ultrasonography-guided Fine Needle Biopsy (EUS-FNB) in patients at Shariati Hospital in Tehran. The study aims to identify risk factors for post-FNB pancreatitis to improve clinical protocols, reduce complications and treatment costs, and increase diagnostic accuracy for pancreatic and biliary tract diseases. The study will collect demographic and clinical data from all eligible patients undergoing EUS-guided FNB during the study period. Amylase and lipase levels will be measured in all enrolled patients 24 hours post-procedure. Pancreatitis will be diagnosed based on abdominal pain and amylase or lipase levels exceeding three times the normal range 24 hours after the procedure. The outcomes will be independently adjudicated by an expert gastroenterologist not involved in the EUS procedures by reviewing participants' medical records. The consensus definition will be applied as a diagnostic framework (rather than a strict definition) so that the adjudicator can use their best judgment in cases that does not strictly satisfy the criteria. The patients will be contacted 24-72 h after the procedure to follow-up on any potential complications. The study plans to enroll at least 300 patients.

EUS-guided tissue acquisition is an advanced diagnostic procedure for evaluating and diagnosing pancreatic, ampullary, and biliary tract tumors due to its high accuracy and minimally invasive nature. However, a potential complication is acute pancreatitis. This can lead to serious clinical problems, including severe abdominal pain, prolonged hospitalization, and, in rare cases, life-threatening complications. EUS-guided FNA of pancreatic masses is infrequently associated with acute pancreatitis. The incidence of pancreatitis after FNA of solid and cystic pancreatic lesions is reported to be 0.64%, and 1.4%, respectively (1, 2). The designs of the tips of FNA and FNB needles are different, and it may have impact on the risk of pancreatitis after FNB. Personal observations of the researchers of this study suggest that the risk of pancreatitis is likely higher after EUS-FNB than EUS-FNA, however, the incidence of pancreatitis after EUS-guided FNB is not systematically studied. The purpose of this study is to determine the incidence of acute pancreatitis after EUS-FNB and identify the risk factors associated with post-EUS-FNB pancreatitis to help prevent and manage this complication, improve clinical outcomes, reduce treatment costs, and enhance diagnostic accuracy for pancreatic and biliary tract diseases. The study is a descriptive analytical study that will be conducted on patients referred to the endoscopy department of Shariati Hospital in Tehran who will undergo EUS-guided FNB.

Patient information, including demographic data and clinical characteristics, will be collected using specialized checklists based on clinical interviews, patient examinations, and review of patient records. The data collected will include gender, age, indication for FNB, history of acute or chronic pancreatitis, and technical details of the procedure, such as the needle brand and size, anatomical location of the biopsy, amount of normal pancreatic tissue the needle passes through, number of passes, and the biopsy site (stomach or duodenum).

All patients meeting the inclusion criteria will be enrolled in the study. Amylase and lipase levels will be measured in all enrolled patients 24 hours post-procedure. Pancreatitis will be diagnosed based on abdominal pain and amylase or lipase levels exceeding three times the normal range 24 hours after the procedure. The outcomes will be independently adjudicated by an expert gastroenterologist not involved in the EUS procedures by reviewing participants' medical records. The consensus definition will be applied as a diagnostic framework (rather than a strict definition) so that the adjudicator can use their best judgment in cases that does not strictly satisfy the criteria. The patients will be contacted 24-72 h after the procedure to follow-up on any potential complications. Patients who develop pancreatitis will receive standard diagnostic and therapeutic follow-up. The study plans to enroll at least 300 patients.

Inclusion Criteria:

Inpatients and outpatients aged 18 years or older undergoing EUS-guided FNB from a solid or cystic lesion in one of the following locations:

• Pancreas
• Ampulla of Vater
• Distal CBD, defined as the intrapancreatic portion of the CBD where the FNB needle passes through the pancreas during biopsy

Exclusion Criteria:

• Patients who undergo concurrent ERCP in the same day
• Patients experiencing an ongoing episode of acute pancreatitis during EUS-FNB
• Patients undergoing EUS-guided FNA
• Uncorrectable coagulopathy (INR > 1.5)
• Uncorrectable thrombocytopenia (platelet < 50,000)
• Decline to participate in the study and sign the informed consent form
• Patients undergoing EUS-guided FNB from the proximal CBD where the FNB needle does not traverse the pancreas

Consecutive inpatients and outpatients aged 18 years or older undergoing EUS-guided FNB at Shariati Hospital

IPD will be shared for collaborative research after reviewing the requester's research protocol

IPD will be accessible following the study's publication and will remain available for three years.

IPD will be shared for collaborative research after reviewing the requester's research protocol